Fix mxint cast (for the last time)

[splogdes]

This pull request includes several changes to the mxint_cast module in the src/mase_components/linear_layers/mxint_operators/rtl/mxint_cast.sv file and updates to the corresponding test file mxint_cast_tb.py. The changes aim to improve the handling of edge cases, enhance the accuracy of calculations, and update test parameters.

Improvements to edge case handling and accuracy:

• Added a condition to handle the case where log2_max_value is zero in the computation of edata_out to avoid potential errors.
• Updated the calculation of shift_value and introduced max_value to ensure accurate handling of large numbers and edge cases.
• Introduced a two's complement function to handle signed arithmetic more effectively and updated conditions for mdata_out to use this function.

Test parameter updates:

• Increased MAX_MANTISSA from 16 to 32 and adjusted the range for in_man and out_man in the get_mxint_cast_config_random function to allow for a wider range of test cases.
• Updated the parameter overrides in the test_mxint_cast_random function to reflect the new maximum values for mantissa and exponent widths.

[luigirinaldi]

crazy stuff right here